5,216 research outputs found
A qualitative exploration of whether lesbian and bisexual women are 'protected' from sociocultural pressure to be thin
Heterosexual women in Western cultures are known to experience body image concerns, dieting and disordered eating as a result of intense social pressures to be thin. However, it is theorised that lesbian and bisexual women belong to a subculture that is ‘protective’ of such demands. Fifteen non-heterosexual women were interviewed about their experiences of social pressure. Thematic analysis of their accounts suggests that such theorising may be inaccurate, because these lesbian and bisexual women did not feel ‘protected’ from social pressures and experienced body dissatisfaction. While they might attempt to resist thin idealisation, resistance is not centred around their sexuality
Motor-driven Dynamics of Cytoskeletal FIlaments in Motility Assays
We model analytically the dynamics of a cytoskeletal filament in a motility
assay. The filament is described as rigid rod free to slide in two dimensions.
The motor proteins consist of polymeric tails tethered to the plane and modeled
as linear springs and motor heads that bind to the filament. As in related
models of rigid and soft two-state motors, the binding/unbinding dynamics of
the motor heads and the dependence of the transition rates on the load exerted
by the motor tails play a crucial role in controlling the filament's dynamics.
Our work shows that the filament effectively behaves as a self-propelled rod at
long times, but with non-Markovian noise sources arising from the coupling to
the motor binding/unbinding dynamics. The effective propulsion force of the
filament and the active renormalization of the various friction and diffusion
constants are calculated in terms of microscopic motor and filament parameters.
These quantities could be probed by optical force microscopy.Comment: 13 pages, 8 figures, 1 Tabl
Solvable Examples of Drift and Diffusion of Ions in Non-uniform Electric Fields
The drift and diffusion of a cloud of ions in a fluid are distorted by an
inhomogeneous electric field. If the electric field carries the center of the
distribution in a straight line and the field configuration is suitably
symmetric, the distortion can be calculated analytically. We examine the
specific examples of fields with cylindrical and spherical symmetry in detail
assuming the ion distributions to be of a generally Gaussian form. The effects
of differing diffusion coefficients in the transverse and longitudinal
directions are included
Force Dependence of the Michaelis Constant in a Two-State Ratchet Model for Molecular Motors
We present a quantitative analysis of recent data on the kinetics of ATP
hydrolysis, which has presented a puzzle regarding the load dependence of the
Michaelis constant. Within the framework of coarse grained two-state ratchet
models, our analysis not only explains the puzzling data, but provides a
modified Michaelis law, which could be useful as a guide for future
experiments.Comment: 4 pages, 3 eps figures, accepted for publication on Physical Review
Letter
A Microscopic Mechanism for Muscle's Motion
The SIRM (Stochastic Inclined Rods Model) proposed by H. Matsuura and M.
Nakano can explain the muscle's motion perfectly, but the intermolecular
potential between myosin head and G-actin is too simple and only repulsive
potential is considered. In this paper we study the SIRM with different complex
potential and discuss the effect of the spring on the system. The calculation
results show that the spring, the effective radius of the G-actin and the
intermolecular potential play key roles in the motion. The sliding speed is
about calculated from the model which well agrees with
the experimental data.Comment: 9 pages, 6 figure
A scanning drift tube apparatus for spatio-temporal mapping of electron swarms
A "scanning" drift tube apparatus, capable of mapping of the spatio-temporal
evolution of electron swarms, developing between two plane electrodes under the
effect of a homogeneous electric field, is presented. The electron swarms are
initiated by photoelectron pulses and the temporal distributions of the
electron flux are recorded while the electrode gap length (at a fixed electric
field strength) is varied. Operation of the system is tested and verified with
argon gas, the measured data are used for the evaluation of the electron bulk
drift velocity. The experimental results for the space-time maps of the
electron swarms - presented here for the first time - also allow clear
observation of deviations from hydrodynamic transport. The swarm maps are also
reproduced by particle simulations
Theoretical Study on Coexistence of Ferromagnetism and Superconductivity
On the basis of a two-dimensional t-t' Hubbard model in ferromagnetic and
paramagnetic states, the triplet superconducting mechanism is investigated by
the third-order perturbation theory with respect to the on-site Coulomb
interaction U. In general, the superconducting state is more stable in the
paramagnetic state than in the ferromagnetic state. As a special case, the
dominant ferromagnetic superconductivity is obtained by the electron-electron
correlation between the electronlike majority and holelike minority bands.
Furthermore, it is pointed out that in some cases the two bands play an
essential role for the coexistence of superconductivity and ferromagnetism.Comment: 5 pages, 10 figure
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